Various powered floor cleaning machines are known in the art. Generally, they comprise a rotating brush or pad unit and a suction unit, usually in the form of so-called squeegees, located behind the brush unit for drawing up the cleaning liquid applied to the ground. Since the squeegee is located on the rear part, such machines can only be operated in one direction. Water pick-up is complicated, if not impossible, when the machine is moved under tables, into edges or dead end areas etc. where it is difficult or impossible to turn the machine around in order to pick up the cleaning solution with the squeegee which is positioned behind the brush or pad. This problem occurs particularly in congested areas which are mostly cleaned with small automatic machines, but it can also occur in connection with bigger machines in super or hyper markets, f.e., if palettes for refilling the shelves are in the way.
Several approaches to attack this problem are known. GB-A-486 499 discloses a floor treating machine wherein the suction unit consists of a suction nozzle which is movably mounted in such a way that its position is variable angularly in a horizontal direction in relation to the brush. U.S. Pat. No. 4,173,056 discloses a floor scrubbing machine having two brushes and a suction unit consisting of a vacuum squeegee water pick-up system the position of which is controlled by a steering arm. Due to the complex design of the movable suction unit, these systems are rather complicated, accident sensitive and expensive.
Another approach consists in providing a second squeegee in front of the brush or pad unit. U.S. Pat. No. 4,817,233 discloses a floor scrubbing machine having a cylindrical scrub brush, a suction squeegee behind the brush and another one in front of the brush, with both squeegees being connected to a vacuumized collection tank. The flexible squeegee lips are mounted in such a way that when the machine is moved forward the lips of the front squeegee fold together and shut off the airflow to it while the rear squeegee remains functional; when the machine is moved backward a reverse action of the squeegee occurs. EP-B-0 792 614 and EP-B-0 800 783 disclose an apparatus for cleaning a ground having a cylindrical brush and suction squeegees in front of the brush and behind the brush. The squeegees comprise a strip of rubber material and are designed in such a way that the rubber wearing component is easily replaceable. However, although there are embodiments available for machines with cylindrical brush units (i.e., machines comprising a cylindrical brush which is rotated around an axis parallel to the surface plane) as well as for machines with disc units (i.e., machines comprising a flat disc being fitted with brushes or pads which is rotated around an axis perpendicular to the surface plane), all of these embodiments have several drawbacks in common. The arrangement with front and rear squeegees makes an air-steering system necessary as the suction performance is limited. Furthermore, the front squeegee in the prior art systems is always in operation, i.e., it always touches the ground. Due to running on dry floor most of the time, this leads to high wear and tear, friction, a higher power-consumption and/or lower suction performance.